The present invention relates to combustion chambers of gas turbine engines and especially aviation gas turbine jet engines, and concerns more precisely a novel non-polluting combustion chamber arrangement.
In known combustion chambers, the fuel is injected into a primary combustion zone followed by a secondary combustion or dilution zone, the primary zone being arranged in such manner that the richness of the fuel-air mixture therein may be close to stoichiometric richness for the conditions of cruising flight (maximum continuous rate) and that its volume may be at least equal to the value which is necessary to ensure re-ignition in flight at a specific altitude. This conventional concept, from the pollution viewpoint, present the following drawbacks:
On idling, while the aircraft is stationary or taxying, by reason of the low means richness if the primary zone, the combustion efficiency is not very good, which involves a significant ejection of carbon monoxide and unburnt hydrocarbons in the vicinity of the ground.
On take-off (maximum rate) and cruising (maximum continuous rate), the combustion efficiency is close to the optimum, but the design of the chamber ensures a long stay of the gases in the zones where the mixture richness is substantially stoichiometric and where the temperature achieved is very high. The combination of this richness and the high values of the temperature and pressure at the entry of the chamber is favourable to the production of various oxides of nitrogen.